Vacuum pump



Dec. 18, 1956 E. J. BEACH 2,774,532

VACUUM PUMP Original Filed Jan. 25, 1945 INVENTOR. Fowmw J. BEACH United States Patent VACUUM PUMP Edward J. Beach, Brooklyn, N. Y., assignor to Beach- Russ Company, Brooklyn, N. Y., a corporation of New York Substitute for abandoned application Serial No. 574,459, January 25, 1945. This application March 5,, 1953, Serial No. 340,444 I I 4 Claims. (Cl. 230-153) I This invention relates to new and useful improvements in vacuum pumps. This is a substitute for my abandoned application, filed on January 25, 1945, Serial No. 574,459.

More particularly, the invention proposes to characterize the new and improved vacuum pump by the fact that it is provided with an elliptically cam-bored cylinder in which the rotor is eccentrically set and provided with a shaft engaging bearings in cylinder heads mounted on the ends of said cylinder.

The invention contemplates forming said cylinder heads with counterbores, or cylindrical recesses arranged c0- axial of the bearings for said shaft, and said recesses being provided with inlet ports in their base walls. The rotor is provided with a slide valve having inlet ports in its edges for aligning with said inlet ports in the bases of said cylindrical recesses. It is proposed to provide rotor end plates on the ends of said rotor and engaging into said cylindrical recesses and having inlet ports aligned with the inlet ports of said slide valve in certain positions of the valve. The invention furthermore proposes, which is the dominating proposal of this invention, to provide cut-01f plates mounted on said rotor end plates and having inlet ports aligned with' the inlet ports of the rotor end plates. Light resilient means is provided for urging these cut-off plates against the bases of said cylindrical recesses.

The unique and most important feature of the improved vacuum pump is the provision of said cut-off plates which revolve with the rotor and which are free to move slightly longitudinally in the head counterbores, or cylindrical recesses. These cut-off plates increase the efficiency of the pump and at the same time control the lubricating and sealing oil to the bearings. They seal against the inlet ports in the bases of said cylindrical recesses by diiferential pressure plus light spring pressure.

When-the pressure side of the slide valve is completing its discharge sweep and approaches the contact, the cutoff plates move across the faces of the inlet ports in the cylinder heads, and momentarily cut-ofi? and isolate the lower vacuum in the line from the higher vacuum in which cylinder, thereby working in unison with the slide valve whose ports are also cut-off until the slide valve I 2,774,532 Patented Dec. 18, 1956 needle valves on the bearings as this only allows a small amount of oil to enter the pump.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanyingdrawings forming 'a material part of this disclosure:

Fig. 1 is a transverse sectional view of a vacuum pump constructed in, accordance with this invention.

Fig. 2 isa horizontal sectional view taken on the line 2.-2 of Fig. 1. I

Fig. 3 is a fragmentary sectional view similar to Fig. 2 but illustrated with certain of the parts separated from each other.

Fig. 4 is an end elevational view looking from the right hand end of Fig. 3.

Fig. 5 is an end elevational view looking from the left hand end of Fig. 3, certain parts being broken away to disclose the interior construction.

Fig. 6 is a fragmentary enlarged detail view of one of the ends of the rotor, to more clearly show a rotor end plate and a cut-off plate, taken on the line 6-6 of-Fig. 7.

Fig. 7 is an elevational view of the rotor shown in Fig. 6 looking towards the right.

The vacuum pump, in accordance with this invention, includes an elliptically cam-bored cylinder 10. Cylinder heads 11 are mounted upon the ends of said cylinder 10 and are provided with bearings 12 for the shaft of the pump. These cylinder heads 11 are also formed with cylindrical recesses, or counterbores 14 arranged coaxially of the bearings 12. The base walls 15 of these cylindrical recesses 14 are provided with inlet ports 16.

A rotor 17 of smaller diameter than'the cylinder 10 is eccentrically mounted therein and is provided with a shaft 18 supportedin the bearings 12. A vane or slide valve 19 is mounted in a slot in the rotor and extends from the rotor 17 into contact with the cylinder 10.

The vane or slide valve has passage means through which the fluid enters the cylinder 10, entering the vane through the inlet port openings 20 and passing from the vane through the openings 17'. The inlet port openings 20 in the vane are located for aligning with the inlet ports were mentioned because of their relationship to the new construction which now will be specifically described.

However, the interior details of the vacuum pump will passes the contact and its inlet ports are again exposed on the suction stroke. In other words, these cut-off plates make it possible to have two points of cut-off, one at the ends of the rotor and the other at the ports on the sides of the slide valve. These two points in addition to the double discharge valves really make three points of cutnot be given in this specification since they form no part of this invention, and they are of a general construction, which will be readily known to those familiar with theart. For those not familiar, attention is called to U. S. Letters Patent No, 2,200,198, to E. I. Beach,

issued May 7, 19 40, which more fully discloses the genofi between the atmosphere of air discharge and the high vacuum side of the pump.

Another function of these sealing plates is to control the sealing-and lubricating oil, thus eliminating certain needle valves on the bearings which are apt to be a source of trouble due to the stuffing boxes and also very delicate adjustments that are necessary on most vacuum pumps. This is accomplished by the "cut-off plates which are closely fitted, and by'the diiferential pressures and the light spring pressures creating a wire drawing effect on the sealing oil making it possible to eliminate the eral construction of that type of a'vacuum pump covered by this invention.

The new construction includes rotor end plates 25 mounted upon the ends of said rotor 17 and engaging .into said cylindrical recesses 14 and having inlet ports 26 aligned with the inlet ports 20 of the slide valve 19 in certain positions of said slide valve. These rotor end platesZS are fixedly mounted on the ends of the rotor 17 with, socket head c ap screws 27. Cut-off plates 29 are mounted upon the rotor end plates 25 and are formed The cut-off plates 29 are mounted upon the rotor end plates 25 with flat head machine screws 32 having their heads countersunk. However, these machine screws 32 do not hold the cut-off plates 29 firmly. They hold these plates 29 loosely, so that there is a small space 34- between the adjacent faces of the cut-off plates 29 and the rotor end plates 25.

Drive pins 35 are mounted upon and project from the rotor end plates 25 and engage into closely fitted openings 36 formed in the cut-off plates 29 for transmitting rotations from the rotor end plates 25 to the cut-off plates 29. It should be noted that these drive pins 35 do no interfere with longitudinal movements of the cut-off plates 29 to and-from the rotor end plates 25.

The cut-off plates 29 are associated with light resilient means for urging said cut-off plates 29 against the base walls of said cylindrical recesses 14, This resilient means is in the nature of several'light compression springs'33 which are housed in small openings 39 formed in the rotor end plates 25 and acting to normally urge the cutoff plates 25 outwards, that is, against the base walls of the cylindrical recesses 14-. In the particular design of the parts shown on the drawings, the inlet ports 30 in the cut-off plates 29 are of square-like shapes but have rounded corners as illustrated clearly in Fig. 7. The inlet ports 16 in the cylinder heads 11 are of kidney shapes as clearly illustrated in Fig. 4.

The operation and advantages of the new construction of the vacuum pump will be clearly understood from the following description:

Since the cut-off plates 29 are mounted upon the rotor end plates 25, the cut-off plates 29 will rotate along with the rotor 17. The springs 38 will force the cut-off plates 29, with a light pressure outwards and against the bases of the cylindrical recesses in the cylinder heads 11. The cut-off plates 29 are free to move slightly longitudinally of the axis of the rotor 17 because of the said spaces 34 between the cut-off plates 29 and the rotor end plates 25.

The cut-off plates 29 will increase the elficiency of the pump and at the same time will control the lubricating and sealing oil to the bearings. They seal against the kidney shaped inlet ports 16 of the cylinder heads 11 by the differential of pressure that exists within the pump, plus the light pressures of the springs 38.

The operation is readily evident. Fluid entering the chamber 19 through the ports or openings 16, 30, 36, 2-9 and 17 is moved therethrough by the vanes 19 and on the compression stroke ports 20 and 26 are out of registry. When the pressure side of the slide valve is completing its discharge sweep and is approaching the point of contact of the rotor with the cylinder, said cutoff plates 29 .move across the faces of the kidney shaped ports 16 and momentarily cut off or isolate the lower vacuum in the line from the higher vacuum in the cylinder, thereby working in unison with the slide valve 19 whose ports are also cut off until the slide valve passes the said contact point and .its inlet ports 29 are again der 1i and is connected with-an oil separation tube, as is described in the above mentioned patent.

Another function of this sealing plate 29 is to control the sealing and lubricating oil, thus eliminating certain needle valves (not shown) on the bearings which are apt to be a source of trouble due to the stufiing boxes and also very delicate adjustments that are necessary on most vacuum pumps. This is accomplished by closely filling the cut-off plates 29 within the cylinder recesses 14, and

by the differential and light spring pressure produced by the springs 38, creating a wire drawing effect on the sealing oil making it possible to eliminate the needle valves on the bearings as this only allows a small amount of oil to enter the pump.

While I have illustrated and described the preferred embodiments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and the right is reserved to all changes and modifications coming Within the scope of .the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is: V

1. in a vacuum pump, an elliptically cam-bored cylinder, cylinder heads mounted on the ends of said cylinder and provided with bearings for the shaft of the pump and also having cylindrical recesses coaxial with said bearings and having flat base walls, inlet ports upon said base walls of said cylindrical recesses, a rotor of smaller diameter than said cylinder mounted eccentrically therein and provided with a shaft supported in said bearings, a slide valve mounted in a slot in said rotor and extending therefrom into contact with said cylinder, said slide valve having inlet ports in its edges for aligning with said inlet ports, rotor end plates mounted on the ends of said rotor and engaging into said cylindrical recesses and having inlet ports aligned with the inlet ports of said slide valve in certain positions of said valve, flat and thin cut-off plates mounted on said rotor end plates and having inlet ports aligned with the inlet ports of said rotor end plates, and, light resilient means for urging said fiat cut-off plates against the base walls of said cylindrical recesses, and outlet means in said cylinder.

2. In a vacuum pump, an elliptically cam-bored cylinder, cylinder heads mounted on the ends of said cylinder and provided with bearings for the'shaft of the pump and also having cylindrical recesses coaxial with said bearings and having flat base walls, inlet ports upon said base walls of said cylindrical recesses, a rotor of smaller diameter than said cylinder mounted ecccntrically therein and provided with a shaft supported in said bearings, a slide valve mounted in a slot in said rotor and extending therefrom into contact with said cylinder, said slide valve having inlet ports in its edges for aligning with said inlet ports, rotor end plates mounted on the ends of said rotor and engaging into said cylindrical recesses and having inlet ports aligned with the inlet ports of said slide valve incertain positions of said valve, fiat and thin cut-off plates mounted on said rotor end plates and having inlet ports aligned with the inlet ports of said rotor end plates, and light resilient means for urging said flat cut-off plates against the base walls of said cylindrical recesses, comprising small helical compression springs mounted in small openingsrin said rotor end plates and in between the-adjacent faces of said cut-off plates and said rotor end plates and outlet means in said cylinder.

3. In a vacuum pump, an elliptically cam-bored cylinder, cylinder heads mounted on the ends of said cylinder and provided with bearings for the shaft of the pump and also having cylindrical recesses coaxial with said bearings and having flat base walls, inlet ports upon said base walls of said cylindrical recesses, a rotor of smaller diameter than said cylinder mounted ecccntrically there- -in and provided'with a shaft supported in said bearings,

a slide valve mounted in a slot in said rotor and extending therefrom into contact with said cylinder, said slide valve having inlet ports in itsedges for aligning with said inlet ports, rotor end plates mounted on-the ends of said rotor and engaging into said cylindricalrecesses and having inlet ports aligned. the inlet ports of said slide valve in certain positions of said valve, flat and thin cut-off plates mounted on said rotor end plates and having inlet ports aligned with the inlet ports of said rotor end plates, light resilient means for urging said flat cut-off plates against the base walls of said cylindrical recesses, comprising compression springs mounted in be tween the adjacent faces .of said cut-off plates and said rotor end plates, said compression springs being housed within small openings formed in one of these adjacent faces and outlet means in said cylinder.

4. In a vacuum pump, an elliptically cam-bored cylinder, cylinder heads mounted on the ends of said cylinder and provided with bearings for the shaft of the pump and also having cylindrical recesses coaxial With said bearings and having fiat base walls, inlet ports upon said base walls of said cylindrical recesses, a rotor of smaller diameter than said cylinder mounted eccentrically therein and provided with a shaft supported in said bearings, a slide valve mounted in a slot in said rotor and extending therefrom into contact with said cylinder, said slide valve having inlet ports in its edges for aligning with said inlet ports, rotor end plates mounted on the ends of said rotor and engaging into said cylindrical recesses cal recesses, and driving pins mounted upon said rotor end plates engaging complementary openings in said cutoff plates, said cut-oft plates being loosely mounted upon said rotor end plates and said rotor end plates being fixedly mounted on said rotor and outlet means in said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS Sorensen Sept. 8, 1931 Beach May 7, 1940 

